The disclosure concerns a method for the operation of a parking brake of a motor vehicle, which comprises at least one wheel brake device, wherein the wheel brake device comprises a driven electric motor for its actuation, which drives a spindle for the displacement of a brake piston of the wheel brake device between a clamping position and a release position, wherein the electric motor is activated for the calibration of the parking brake in order to displace the brake piston into the release position in a first step and from the release position towards the clamping position in a subsequent second step.
The disclosure also concerns a corresponding parking brake, as well as a computer program and a computer program product.
Methods of the aforementioned type are known from the prior art. Parking brakes for motor vehicles generally comprise two wheel brake devices, each associated with a wheel of a rear axle of the motor vehicle in order to lock the same as required. The wheel brake devices are usually provided with an electric motor actuator for this that drives a brake piston of the respective wheel brake device in order to produce a brake force. In this case the brake piston is usually actuated by a spindle that is driven by an electric motor.
A complete and accurate mathematical description of the system dynamics of the parking brake is possible through accurate knowledge of the motor parameters of the electric motor. Besides the motor constant and the motor impedance, the moment of inertia is also a motor parameter that describes the dynamics of the parking brake and is subject to a production spread as with the other motor parameters.
During the initial commissioning or during ongoing operation of a parking brake, it is advantageous if the same is calibrated, in particular in order to know the position of the spindle or of the brake piston for activation of the wheel brake device. During this it is known to calibrate the parking brake by activating the electric motor in order to displace the brake piston into a release position in a first step, and into a clamping position in a subsequent second step. In the release position the brake piston is moved into a non-use position, and in the clamping position the brake piston acts in particular on a brake disk with a brake force. Between the two positions, the brake piston can be displaced by the electric motor, in particular by a spindle that can be driven by the electric motor. By approaching said two end positions, which are characterized by any further movement of the brake piston not being mechanically possible, the parking brake and in particular the electric motor actuator can be calibrated.